Mixed yarn and fabric



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MIXED YARN AND FABRIC 2 Sheets-Sheet 2 Filed March 1, 1946 Patented Aug.2, 1949 UNITED STATES PATENT OFFICE MIXED YARN AND FABRIC ChandlerRobbins, II, Auburn, Maine Application March 1, 1946, Serial No. 651,406

(Granted under the act of March 3, 1883, as amended April 30, 1928; 3700. G. 757) 9 Claims.

The invention described herein, if patented, may be manufactured andused by or for the Government for governmental purposes, without thepayment to me of any royalty thereon.

This invention relates to a base fabric for coating, and moreparticularly to a base fabric comprising a mixture of high-tenacityfibers having relatively poor adhesion to a natural or artificial resinor rubber coating and of lower-tenacity fibers having relatively strongadhesion to such coating.

The use of highly polymerized synthetic fibers, such as nylon, rapidlyincreases in the textile art because of their numerous advantages amongwhich are strength, elongatability, and attractive appearance. However,it has been found heretofore that it was not feasible to coat thesefibers with conventional natural or synthetic resin or rubber coatingsin such a manner as to secure a strong bond between the base fabric andthe coating; on the contrary, the experience of the art has been that acoating applied to a nylon fabric will peel off after a comparativelyshort period of wear. As a consequence, the durability of nylon andother highly polymerized synthetic fabrics as used in the manufacture ofwaterproof clothing has never been fully satisfactory; although thesynthetic threads are waterproof, water will leak through theinterstices between the threads in the fabric after the coating has wornoff. Synthetic fabrics coated on one side only have shown particularlybad wearing characteristics.

An object of the present invention therefore is a base fabric for theapplication of coating, which combines the advantages of the strength,elongatability and appearance of highly polymerized synthetic fibers,with good adhesion to coating which heretofore has been lacking infibers of this type.

Another object of the present invention is a mixed fabric suitable forthe application of a coating thereto, which is made of a yarn composedof high-tenacity threads having poor adhesion to the coating and oflower-tenacity threads having good adhesion to coating.

A further object of this invention is a base fabric for the applicationof a coating, which combines great strength, light weight, and strongadhesion to the coating.

Yet another object of the invention is a mixed yarn composed of threadsdiffering in tenacity, elongation and adhesion to coatingcharacteristics, and a method of combining them in such a manner thatthe ultimate elongation of the two materials is equal at the breakingpoint of the composite yarn.

And another object of the present invention is clothing and coveringmade of highly polymerized synthetic threads, permanently waterproofed,fireproofed, mothproofed, or mildew proofed by a coating stronglyadhering to the completed fabric.

Another object of the invention is a fabric comprising highlypolymerized synthetic threads, which is coated only on one side with afirmly adhering coat.

The foregoing and other objects of the present invention are accompaniedby combining (1) a highly polymerized synthetic thread, such as nylon,which has great strength and elongatability, while, however, beingsubstantially inelastic as compared with rubber threads, but pooradhesion to coating and (2) a thread of lower tenacity andelongatability but good adhesion to coating, e. g., cotton, into acomposite yarn by twisting the less elongatable thread around the moreelongatable thread in a spiral unbonded to the latter thread, making afabric from the composite yarn, and applying a coat or a number of coatsto the fabric.

The appended drawings illustrate a composite yarn, suitable for making abase fabric for coating in accordance with the present invention.

Fig. 1 shows a two-component composite yarn in the untensioned state,and

Fig. 2 shows the same yarn in the tensioned state.

Figure 3 shows a three-component yarn in the untensioned state.

Figure 4 shows the three-component yarn of Figure 3, but in thetensioned state.

Figure 5 is a plan view of a coated fabric; and

Figure 6 is an enlarged section through the fabric of Figure 5 alonglines 6--6, showing crossed composite filling and warp threads coated onone side, in accordance with the present invention.

Reference numeral H in the drawings denotes It is believed that thecause of poor adhesion of coating to highly polymerized syntheticfabrics, such as highly polymerized linear polyamides (nylon), is thesmooth surface thereof which prevents a strong bond between fabric andcoating. On the other hand, most natural and some artiflcial fibers showunder the microscopic a scaly or corrugated surface, and yarns spun withrelatively short natural fibers have on their surface short ends ofscaly or corrugated fibers to which applied coating may become bonded,and their strong adhesion to coating is thought to be due to theseproperties.

A fabric composed of highly polymerized synthetic smooth threads andother threads with a scaly surface possesses merit in having much betteradhesion characteristics than a fabric consisting solely of highlypolymerized synthetic threads. In a base fabric consisting exclusivelyof highly polymerized synthetic fabrics, such as nylon, the adhesion ofthe coating to the fabric is not due to adhesion of the coating to thethreads, but to adhesion of the coat of one side of the fabric to thecoat on the other side of the fabric through the interstices between thethreads. Such adhesion is obviously poor and the coating will quicklypeel off; when the base fabric is flexed or creased, the bond betweenthe two layers .of coating will crack, which leads to quickdeterioration of the coating. Where, however, as in the proposed mixedfabric, the coating adheres to the threads themselves, the coating willfiex with the fabric and thus permanently adhere to its base.

In order to obtain a base fabric suitable for the application ofcoating, wherein not only a strong bond exists between the base and thecoating, but where the elongatability and strength of the yarn composingthe fabric bears the most favorable relation to its weight, it has beenfound that such a yarn can be obtained by combining a high strengthmaterial such as nylon yarn with a, yarn such as cotton, by either atwisting or spinning process to form a composite yarn of nylon andcotton. This may be carried out on conventional twisting and spinningmachinery used either in the silk throwing or cotton twistingindustries. The yarn thus formed is then woven into a fabric which, whencoated by conventional methods, such as calenderizing or spread coating,forms a waterproof fabric for the manufacture of suchitems as raincoats,ponchos, boots, coverings, compactly folding lifeboats, etc. Thesefabrics have high strength in relation to weight, as compared withconventional base fabric, such as cotton or rayon. The coat applied tothe mixed fabric will have an adhesion thereto several times greaterthan that of a coating film to fabrics composed solely of nylon or othersmooth threads to which the coating films do not adhere to anyappreciable degree, and which can be quickly rubbed ofl from the base. Acoat applied to the mixed fabric will firmly adhere thereto, even if itis applied to only one side of the mixed fabric.

It has further been found that the mixed fabric can be made in such amanner that it retains the high'strength and elongatability of thesynthetic material, if the yarn composing the fabric is made in thefollowing manner. A cotton yarn having a relatively high number of turnsper inch, is twisted around a nylon yarn, preferably in a directionopposite from that in which the cotton yarn was originally spun. Thecotton yarn thus forms a loose spiral around the nylon yarn. When thecomposite yarn is placed under stress, a considerabie amountof strainmust then occur before the cotton fibers become taut. For example, ahigh tenacity nylon yarn requires approximately 20% elongation before itbreaks, while cotton yarn breaks after an elongation of onlyapproximately 10%. It is thus possible to form a composite yarn,consisting of a spiral in which the nylon may be stretched 10% beforethe cotton becomes taut; and upon reaching the ultimate elongation point(20%) of the nylon, both the cotton and the nylon will break at the sametime. The full tenacity of both the cotton and the nylon is thusutilized in resisting strains up to the breaking point. By winding thecotton yarn around the nylon yarn in a direction opposite to the one inwhich the cotton yarn was originally twisted, the threads composing thecotton yarn are partly untwisted, which enlarges the surface of cottonmaterial to which the coatin may adhere.

The following examples illustrate a particular instance of an actualapplication of the present invention, but do not constitute a limitationof the invention to the specific materials and figures set forth in theexamples:

Example I A fine cotton yarn of 10 yards in length and having elongationcapacity of 10%, containing 32 turns per inch, is placed adjacent to astrand of untwisted nylon of 10 yards length, the nylon having anelongation capacity of 20%. The two textiles are then twisted in adirection opposite to the direction of the twist originally in thecotton yarn. This action causes a reduction in the helix angle of thefibers in the cotton yarn and an increase, therefore, in the totallength of. the cotton yarn which distributes itself along the length ofthe nylon yarn. If, for example, the combination yarn is turned 19 turnsper inch, the result gained in the length of the cotton yarn may beapproximately 8%, whereas the increase in the helix angle of the fibersin the nylon yarn may shorten the nylon approximately 2%, thus making anover-all diiferential of 10% between the two components in the yarn. Thecomposite yarn is placed in a testin machine and elongated to a lengthof 11 yards; the nylon component of the yarn is now under stress, whilethe cotton spiral is taut but unstressed. Upon further elongation to alength of 12 yards, the point of ultimate elongation of the nyloncomponent and of the cotton component is reached, and any elongationbeyond 12 yards will result in breakage of the composite yarn.

Example II A composite nylon and cotton yarn made in the manner andproportions set forth in Example I is woven into a fabric, and apolyvinyl chloride film is applied to the fabric by calenderizing orspread coating. The resulting coated fabric has substantially the samestrength as the sum of the strength of a pure nylon fabric, containingan amount of nylon equal to that contained in the combined fabric, plusthe strength of a cotton fabric, manufactured with an amount of cottonequal to the amount of cotton used in the combined fabric; and has anelongatability substantially the same as a pure nylon fabric and hassubstantially the same good adhesion of the coating as a pure cottonfabric.

While the foregoing examples particularly mention nylon, a highlypolymerized synthetic. linear polyamide, it must be understood thatother synthetic fabrics, such as vinyl yarns, may be employed instead ofnylon. Other yarns suitable in place oi nylon are high-tenacity rayonand other high-tenacity regenerated cellulose fibers.

Similarly, while cotton has been mentioned as an example of acomparatively low strength and low elongatability textile which,however, possesses good adhesion to coating, other textiles, such aswool, linen, sisal, hemp, flax, and jute may take its place. Silk alsomay be used in lieu of cotton, provided that the textile with which itis combined has a tenacity and elongatability exceeding that of silk;nylon is a textile which excels over silk in these properties. A mixedfabric of rayon and of another textile exceeding rayon in tenacity andelongatability is also within the scope of the present invention.

Examples of coatings suitable for application to a mixed fabric inaccordance with the present invention, in addition to polyvinylchloride, are cellulose nitrate, linseed oil, neoprene, butyl rubber,butadiene polymer synthetic rubber, natural rubber, and, in fact, allother coatings for fabrics that are now known to the art.

The lengths of the component textiles in the composite spiralillustrated in Fig. 1 are functions of the helix angles of the yarnswhich make up the. spiral. The helix angle of a strand of untwistedparallel filaments is and the helix angle approaches 90 the more tightlytwisted the yarn is; if parallel filaments are twisted to form a yarn,the length of the twisted yarn is obviously less than that of theparallel filaments prior to twisting and the length of the yarndecreases with each additional twisting turn. 0n the other hand, if ahighly twisted yarn is partly untwisted, its helix angle decreases,while its length increases. By twisting together an untwisted strand (ora low-twist yarn) and a comparatively highly twisted yarn in a directionopposite to the direction of the twist of the latter yarn, the length ofthe former is caused to decrease because it becomes more tightly twistedwith every additional turn, and the length of the latter is caused toincrease, inasmuch as each additional turn in a direction opposite tothe direction of the original twist of the latter yarn progressivelyuntwists it. The number of turns necessary for increasing the length ofa highly twisted yarn to a predetermined length by partly untwisting itvaries with the diameter of the filaments composing the yarn, and can bedetermined by simple experimentation (such as counting the number ofturns necessary for increasing the length of a -yard sample of highlytwisted cotton yarn to 11 yards).

The length to which each component textile which goes into the compositespiral is to be adjusted is calculated in the following manner:

The length of the more elongatable component ii of the spiral equals thelength of the spiral itself; and the length of the less elongatablecomponent l2 equals that of an untensioned strand of the lesselongatable component which, when stretched to the breaking point, willcorrespond to the length of the more elongatable component at the pointof ultimate elongation of the latter. Thus, in the foregoing Example I,the 10 yards of high tenacity nylon will have a length of 12 yards atthe point of ultimate elongation the length of a strand of cotton (10%elongation) which will break at 12 yards is about 11 yards (exactly l011 yards); consequently 10 yards of untensioned composite yarn willcontain cotton yarn wound in a loose spiral around nylon in a ratio of11 to 10, that is, 11 yards of cotton yarn around 10 yards of nylon. Ifinstead of nylon another synthetic textile having only. 15% elongationcapacity is chosen, the ratio is 10.5 (cotton) to 10 (synthetic textile)inasmuch as a 10-yard strand of a synthetic textile with'15% elongationcapacity will break when stretched to 11 /2 yards. and the length of acotton strand (10% elongation capacity) which breaks when stretched tothe same length of 11 yards is about 10 yards (exactly 10 /11 yards).Conversely, if the composite yarn consists of nylon (20% elongationcapacity) and a grade of silk having only 15% elongation capacity, but abetter adhesion to coating than nylon, the ratio between nylon and silkin the spiral will be 10 to approximately 10.5 (more exactly, 10.435)the latter figure is computed by ascertaining the length of anuntensioned strand of silk which, when stretched 15%, will break at anultimate elongation to 12 yards (correspondin to the ultimate elongationof a 10-yard strand of nylon).

The length of the untensioned less elongatable material always exceedsthat of the untensioned more elongatable material, inasmuch as theformer is wound in a loose spiral around the latter.

A composite yarn in accordance with the present invention may alsoconsist of three or more different materials, differing in strength,elasticity, and adhesion to coating, or in any one or two of thoseproperties. The lengths of materials needed to make a composite yarnwhich will break at the point orultimate elongation of the componenthaving the greatest elongatability, are computed in the same manner asis the case of a composite yarn composed of only two difierentmaterials; thus in the case of a composite 10 yard yarn of cotton- I2(10% elongation capacity), silk I3 (15% elongation capacity) and nylonll (20% elongation capacity), the ratio is 11 to 10.5 to 10; that is, ina 10 yard composite spiral, an 11 yard helix of partly untwisted cottonyarn and a 10 /2 yard helix of partly untwisted silk yarn are wound in aloose spiral around a 10 yard core of nylon.

As in the case of a composite yarn comprising two diflerent materials,best coating results are obtained in a yarn composed of three or moredifferent yarns, if the yarns having relatively lesser elongatabilitybut good adherence to coatin are wound around the more elongatable, butsmooth and poorly coat-adhering material in a direction opposite to thedirection in which the less elongatable yarns were originally twisted.

It is to be understood that the examples and specific figures given inthe foregoing description are only for purposes of illustration and arenot to be deemed to constitute a limitation of the scope of theinvention. It is obvious that substitutions of equivalent materials withcharacteristics suitable for attaining the objects of the invention willreadily occur to the expert; and such substitutions are within thespirit and scope of this invention. I desire to claim my inventionbroadly and to be limited only by the appended claims.

I claim:

1. For use in a coated fabric, a composite yarn of great breakingstrength and having good ad esion to coating, comprising a highlypolymerized synthetic thread and a twisted natural textile yarn formingan unbonded spiral around the same, saidnatural textile yarn having arougher surface and lesser elongatability than said synthetic thread,the length of the filaments of said twisted natural textile yarn in theuntensioned state being greater than the length or said synthetic threadby an amount substantially equaling 7 the difference between the amountsby which said natural filaments and said synthetic material arerespectively elongatable prior to. breaking, said synthetic and naturalmaterials being of substantially the same length at their point ofultimate elongation.

2. For use in a coated fabric, a composite yarn having great breakingstrength and good adhesion to coating, comprising nylon thread and atwisted cotton yarn having a rougher surface than said nylon and formingan unbonded spiral around said nylon, the length of said cotton yarndiflering in the untensioned state from the length of said nylon in theuntensioned state by an amount substantially equaling the differencebetween the amounts by which said nylon and said cotton are respectivelyelongatable prior to breaking, and said nylon and cotton being ofsubstantially the same length at their point of ultimate elongation.

3. A textile base for a coating, said textile base having great breakingstrength and good adhesion to coating and comprising a substantiallyinelastic composite yarn, said composite yarn comprising asmooth-surface textile material core and a yarn comprising textilematerial less elongatable than and having better adhesion to coatingthan said first-named textile material and forming an unbonded spiralaround said first-named textile material, said core and said last-namedyarn being of substantially equal length at their point of ultimateelongation, and the length of the filaments of said last-named yarndiffering in the untensioned state from the length of said core by anamount substantially equal to the diiference between the amounts bywhich said textile materials are respectively elongatable prior tobreaking.

4. A coated textile fabric comprising a textile base and a coating onsaid textile base, said textile base comprising substantially inelasticcomposite yarn of great breaking strength and having good adhesion tocoating, said composite yarn comprising a smooth-surface textilematerial core and a yarn comprising textile material less elongatablethan and having better adhesion to coating than said first-named textilematerial and forming an unbonded spiral around said firstnamed textilematerial, said core and said lastnamed yarn being of substantially equallength at their point of ultimate elongation, and the length of thefilaments of said last-named yarn differing in the untensioned statefrom the length of said core by an amount substantially equal to thedifference between the amounts by which said textile materials arerespectively elongatable prior to breaking.

5. A coated textile fabric comprising a textile base and a coating onsaid textile base, said textile base comprising composite yarn of greatbreaking strength and having good adhesion to coating, said compositeyarn comprising a highly polymerized synthetic thread and a twistednatural textile yarn forming an unbonded spiral around the same, saidnatural textile yarn having a rougher surface and lesser elongatabilitythan said synthetic thread, the length of the filaments of said twistednatural yarn in the untensioned state being greater than the length ofsaid synthetic thread by an amount substantially equaling the diiferencebetween the. amounts by which said natural filaments and said syntheticmaterial are respectively elongatable prior to breaking, said syntheticand natural materials being of substantially-the same length at theirpoint of ultimate elongation.

8. A coated textile fabric comprising a textile base and a coating onsaid textile base, said textile base comprising composite yarn of greatbreaking strength and having good adhesion to coating, said compositeyarn comprising nylon thread and a twisted cotton yam having a roughersurface than said nylon and forming an unbonded spiral around saidnylon, the length of said cotton yarn differing in the untensioned statefrom the length of said nylon in the untensioned state by an amountsubstantially equaling the diilerence btween the amounts by which saidnylon and said cotton are respectively elongatable prior to breaking,and said nylon and cotton being of substantially the same length attheir point of ultimate elongation.

'7. A coated fabric comprising: a textile base of great breakingstrength and good adhesion to coating, said textile base comprisingsubstantially inelastic composite yarn, said composite yarn comprising asmooth-surface textile material core and a yarn comprising textilematerial less elongatable than and having better adhesion to coatingthan said first-named textile material and forming an unbonded spiralaround said firstnamed textile material, said core and said lastnamedyarn being of substantially equal length at their point of ultimateelongation, and the length of the filaments of said last-named yarndiffering in the untensioned state from the length of said core by anamount substantially equal to of said twisted natural the differencebetween the amounts by which'said textile materials are respectivelyelongatable prior to breaking; and a coating on only one side of saidfabric.

8. A coated fabric comprising a textile base of great breaking strengthand good adhesion to coating, said textile base comprising compositeyarn, said composite yarn comprising a highly polymerized syntheticthread and a twisted natural textile yarn forming an unbonded spiralaround the same, said natural textile yam having a rougher surface andlesser elongatability than said synthetic thread, the length of thefilaments textile yarn in the untensioned state being greater than thelength of said synthetic thread by an amount substantially equaling thedifference between the amounts by which said natural filaments and saidsynthetic material are respectively elongatable prior to breaking, saidsynthetic and natural materials being of substantially the same lengthat their point of ultimate elongation; and a coating on only one side ofsaid fabric.

9. A coated fabric comprising a textile base of great breaking strengthand good adhesion to coating, said textile base comprising compositeyarn, said composite yarn comprising nylon thread and a twisted cottonyarn having a rougher surface than said nylon and forming an unbondedspiral around said nylon, the length of said cotton yarn difiering inthe untensioned state from the length of said nylon in the untensionedstate by an amount substantially equaling the difference between theamounts by which said nylon and said cotton are respectively elongatableprior to breaking, and said nylon and cotton being of substantially thesame length at their point of ultimate elongation; and a coating on onlyone side of said fabric.

CHANDLER ROBBINS, 11.

(References on following page) REFERENCES CITED The following referencesare of record In the file of this patent:

Number UNITED STATES PATENTS Name Date Metcalf Jan. 9, 1906 Jen-ems June30, 1908 Farrell Feb. 7, 1928 Brewster Feb. 21, 1928 Rochester Oct. 17,1933 A1168 Sept. 1, 1936 Number 10 Number

